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Personal Armour Testing versus Small Arms Ammunition when the Test Standard Doesn’t Fit

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Small arms ammunition which may impact personal armour and is deemed to be realistic as a threat by the user, may not always comply with armour test standards. In many cases there are good practical reasons why such realistic ammunition is not included in standards, including availability and variability. However, when using some test standards, approximate equivalents have been made between realistic ammunition and those levels available within the standards, for example, the use of 30.06 AP M2 as an alternative to 7.62 x 54R B32 API. Some weapon systems not represented within test standards, are not possible to be replaced by any test level listed in any test standard. For example the Heckler and Koch MP7 and FN P90, which are positioned in performance between handgun and rifle levels. Many armour specifiers and users will make minor modifications to levels in armour standards in order to allow the test method to be valid, but with slightly different ammunition types included within a specific level. For example NIJ 0101.06 Level III+ is often specified usually for materials-based reasons. Finally the paper will introduce how bullet surrogate projectiles may be an answer to some of the issues previously highlighted.
Content may be subject to copyright.
This paper is based on the work presented at the 10th International Armament Conference on „Scientific Aspects of Armament and Safety
Technology”, Ryn, Poland, September 15-18, 2014.
Personal Armour Testing versus Small Arms Ammunition
when the Test Standard Doesn’t Fit
Philip L. GOTTS*
Phil Gotts Consulting Ltd., 23 Thorney Rd, Capel St Mary, Ipswich, Suffolk, IP9 2HL,
United Kingdom
*corresponding author, e-mail: phil@philgotts.com
Manuscript received May 28, 2014. Final manuscript received February 27, 2015
DOI: 10.5604/20815891.1185940
Abstract. Small arms ammunition which may impact personal armour and is deemed to
be realistic as a threat by the user, may not always comply with armour test standards.
In many cases there are good practical reasons why such realistic ammunition is not
included in standards, including availability and variability. However, when using some
test standards, approximate equivalents have been made between realistic ammunition
and those levels available within the standards, for example, the use of 30.06 AP M2 as
an alternative to 7.62 54R B32 API. Some weapon systems not represented within test
standards, are not possible to be replaced by any test level listed in any test standard.
For example the Heckler and Koch MP7 and FN P90, which are positioned in
performance between handgun and rifle levels. Many armour specifiers and users will
make minor modifications to levels in armour standards in order to allow the test
method to be valid, but with slightly different ammunition types included within
a specific level. For example NIJ 0101.06 Level III+ is often specified usually for
materials-based reasons. Finally the paper will introduce how bullet surrogate
projectiles may be an answer to some of the issues previously highlighted.
Keywords: mechanics, ammunition, armour, test standard
PROBLEMS OF MECHATRONICS
ARMAMENT, AVIATION, SAFETY ENGINEERING
ISSN 2081-5891
6, 4 (22), 2015, 19-30
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P.L. Gotts
20
1. INTRODUCTION
In order to determine the efficacy of a personal armour system it must
undergo some level of testing. As the primary aim of a personal armour system
is to protect the wearer from impacting objects, it therefore seems sensible that
the primary testing regime is that of the item’s resistance to such impacting
objects. Although impacting objects may be fragmentation, bullets, blades or
even blunt objects, this paper focusses upon personal armour designed
specifically for the defeat of small arms ammunition.
Some personal armour systems manufactured for the defeat of small arms
ammunition are designed to meet the requirements of a specific theatre or
operation and therefore potentially for a specific threat regime. However, it is
much more common for the personal armour to be designed for a more generic
threat regime.
If a personal armour is designed for the defeat of a specific threat regime, it
then requires testing to confirm that it meets these relevant protection
requirements. Therefore a test method or standard needs to be chosen which is
relevant to the requirement for the protection. This decision regarding the test
method or standard is often not as simple as it may initially seem. The conflict
within the decision-making process is often due to a difference between the
reality of the threat and what is available to use within the available test
methods or standards.
1.1. Test Methods or Standards Available for Personal Armour
versus Small Arms Ammunition
Unless the test method or standard is bespoke and hence is written
specifically for a single personal armour or suite of armour systems, it will be
one designed to be relevant for a potentially very wide range of personal armour
systems. In most cases a widely used test method or standard has been written
with a specific user or stakeholder community in mind. In fact it may well have
been written by members or representatives of that stakeholder community.
Probably the best known example of this is the NIJ-0101.0n series of test
standards (for the purpose of this paper only the .04 and .06 versions will be
considered). However, other test methods or standards are also available.
1.1.1. NIJ-0101.0n [1, 2]
The NIJ-0101.0n series of standards is one developed specifically for the
US Law Enforcement community. The first version was released in March 1972
as NILECJ-0101.00.
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Personal Armour Testing versus Small Arms Ammunition when the Test
21
Over the six versions of the standard since that time, the standard has
always included a number of both low velocity and high velocity bullet levels.
These have changed over the versions, and with the latest two versions the
change in levels has made the utilisation for other stakeholder communities
slightly more difficult to justify.
The NIJ-0101.0n standards have historically been used by stakeholders
outside the originally intended US Law Enforcement one. One community that
has used the NIJ-0101.0n standards extensively is the military one. For the
military community the most common NIJ-0101.0n levels specified are levels
IIIa, III and IV. Level IV refers to the 30.06 AP M2, which has been a level in
the standard since the original NILECJ-0101.00. Level III was introduced in the
NIJ-0101.01 version and consists of the M80 7.62 51 mm NATO ball. Level
IIIa was introduced as the high handgun level in the NIJ-0101.02 and consisted
of a .44 Magnum and a 9 mm FMJ. On many occasions this level has been
specified by the military community, but only for the 9 mm FMJ. However,
there was a change for the NIJ-0101.06 Level IIIa, which replaced the 9 mm
FMJ with a .357 FMJ. This change reduces the relevance of this level of the NIJ
standard for the military community, and it is for this reason that many military
specifiers still refer to NIJ-0101.04.
1.1.2. HOSDB 2007 [3]
The HOSDB standard is the UK’s equivalent to the NIJ-0101.0n. It was
developed for the UK Police forces and has mainly been used for that specific
user community only.
1.1.3. VPAM APR 2006 [4]
VPAM APR 2006 is a test standard produced by the VPAM association.
The VPAM is an association of German-speaking test organisations, who have
developed their own suite of test standards.
VPAM APR 2006 includes a very wide range of small arms ammunition
with .22 LR at the lower end and 14.5 114 mm at the upper end. This standard
also includes both Western and former Eastern Bloc ammunition types, thus
allowing a greater potential for reality for the various user communities.
1.1.4. GOST R 50744-95 [5]
This standard is the Russian test standard for body armour. It includes
levels which are probably considered to be realistic for Western nations.
However, they are also levels which may be considered to incorporate a higher
level of variability.
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P.L. Gotts
22
2. REALITY VERSUS THE TEST METHOD
Sometimes the reality of the situation for which the personal armour is
required, is one which is difficult to reproduce with any available test method or
standard. Some of these aspects include the test levels, behind armour blunt
trauma and shot patterns.
2.1. Test Levels
The most obvious, and probably most critical, of these is that of
ammunition chosen for the test levels. It is most common for the ammunition
chosen for the test standard levels to be those originating within the country
from which the test standard was authored. For example the ammunition types
in the NIJ standards are of US manufacture, those in the HOSDB standard are
easily available in the UK and those in the GOST standard are of Russian
origin. The VPAM includes ammunition types from a number of different
sources. However, it is possible that the more realistic threats to the end user
may be from different sources. One way in which this issue has been addressed
by some users will be discussed later.
2.2. Behind Armour Blunt Trauma (BABT)
Behind Armour Blunt Trauma is an injury caused to the body, when the
armour has defeated the incoming projectile. For body armour covering the
torso the injury can include bruising, rib fractures, lung injury and even
commotio cordis (commotio cordis occurs when the heart is stopped, due to an
impact to the chest. It occurs only in specific times during the cardiac cycle).
For helmets the injuries could include skull fracture, diffuse axonial injury, or
traumatic brain injury.
In body armour test standards BABT as such is not measured. However, in
its place the back-face signature (BFS) caused by the deforming armour into
a modelling clay is used. The allowable BFS is of a different threshold value
within different standards. For example the NIJ standards specify a maximum
BFS of 44 mm, the HOSDB 25 mm or 44 mm (for the HG1A level only), and
the GOST 17 mm. The VPAM refers the test organisation to the specific
product requirement in this matter.
Many people refer to the BFS as ‘the trauma’, but this is incorrect. The
trauma is the injury and the BFS is the measurement method. There is very little
evidence that the injury and the BFS can be correlated, and that which does
exist is for very specific cases only, such as a .38 Special versus seven layers of
Kevlar at an impact velocity of 244 m/s. This lack of correlation evidence was
highlighted in a US OSC report in 1992 [6].
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Personal Armour Testing versus Small Arms Ammunition when the Test
23
However, this limited data has somehow been sufficient for this BFS
method to become incorporated into many body armour standards, since it was
first included within NIJ-0101.01 in 1978. It is now very difficult to come to
any agreement to move away from such a measurement, as this could be seen as
lowering the standard and hence reducing the protection offered by the armour.
In the UK a decision was made to change from the 44 mm limit of the NIJ to
25 mm, but the evidence for why this was done is largely lost in history. After
many years of consideration, the UK Home Office is now relaxing some levels
of BFS back to 44 mm.
These BFS levels have become accepted as being an important part of the
test standard, even though there is very little evidence which connects the levels
to injury. The question should also be asked as to which actual injuries are the
BFS measurements actually related to. Considering body armour only bruising
can be considered to be related to BFS, but this is a relatively minor injury. It
was thought that rib fractures were also caused by displacement of the armour,
but there is now emerging evidence that rib fractures may actually be a stress
wave related injury [7]. The lung injury seen behind armour is similar to blast
lung type injuries and hence is a stress wave induced injury and not
displacement induced. Commotio cordis is also a stress wave induced injury.
Incorporation of these BFS levels in body armour test standards has led to
body armour being designed to meet the BFS requirement over and above the
ballistic requirement, which has ultimately led to less flexible armour systems.
Less flexible armours are less comfortable and hence increase the burden on the
wearer. Therefore it could be argued that body armour is made to be less
comfortable by an aspect of the standard that only reduces what is actually
a very minor injury.
An additional criticism which can be aimed at the BFS measurement
methods is that they may be variable in their outcome. Figure 1 below shows
more than 400 shots versus the same design of soft body armour using the same
type of ammunition. The firings were all conducted using Roma Plastilina
Number 1 over a test period of four years. The Plastilina was replaced at the
recommended intervals within the relevant test standard.
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P.L. Gotts
24
Fig. 1. Graph of Back-Face Signature versus Impact Bullet Velocity
Considering the bullet impacts at 365 m/s (HOSDB HG1) or 373 m/s (NIJ-
0101.04 Level IIa), it is possible for the armour to either pass or fail the BFS
requirement for both HG1 (25 mm) and NIJ-0101.04 Level IIa (44 mm). The
particular armour is known to be consistent in its behaviour, as is the
ammunition type. Therefore this would indicate there to be variability in the test
method.
3. AMMUNITION EQUIVALENCE
If an ammunition type which is considered to be realistic is not included
within a test method or standard, the armour specifier may determine that an
ammunition type which is within a test standard, may be similar enough to the
required threat to be used. One commonly assumed equivalence is between the
7.62 54R B32 API and the 30.06 AP M2. This may or may not be a sensible
equivalence. Gotts et al [8] showed that versus an armoured steel target, most
versions of the B32 API provide a higher performance than the 30.06 AP M2.
4. IN-BETWEEN THREATS
Unlike the previous case, in which an attempt is made to use an available
or more realistic ammunition type to replace one in the test method or standard,
there are cases where there is really no equivalent ammunition available. Two
specific weapon systems which are not included in test methods or standards,
but which could be an encountered threat, are the FN P90 and the H&K MP7.
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Personal Armour Testing versus Small Arms Ammunition when the Test
25
These two weapons are designated as personal defence weapons by the
manufacturers and as such they are expected to replace a pistol for those
personnel who do not have the requirement for an assault rifle. These two
weapon systems can be seen in Figure 2 and 3. Table 1 compares the P90 and
the MP7.
Table 1. Comparison of P90 and MP7
Category
H&K MP7
Calibre length (mm)
4.6 30
Muzzle velocity (m/s)
725
Bullet mass (g)
1.6
Kinetic Energy at muzzle (J)
420
The design of these weapons and ammunition is such that they will defeat
textile personal armour with ease, but will be defeated easily by ceramic plates.
The 540 J kinetic energy at the muzzle of the P90 is lower than the 713 J of
a 9 mm FMJ at 398 m/s (NIJ-0101.06 Level II), but the effects versus textile
body armour are much more serious. The kinetic energy density, however, for
the P90 is 5.3 J/mm2 compared to 2.8 J/mm2 for the 9 mm. The kinetic energy
density for the MP7 at muzzle velocity, for comparison is 6.3 J/mm2.
Comparison with a typical high velocity bullet type from a test standard could
be the 7.62 51 mm M80 NATO ball as per NIJ-0101.06 Level III. This would
have a kinetic energy at the muzzle of 3.44 kJ and a kinetic energy density of
18.8 J/mm2. These comparisons, as well as those for the NIJ-0101.06 Level IIIa
ammunition types, can be found in Table 2.
Fig. 2. H&K MP7
Fig. 3. FN P90
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P.L. Gotts
26
Table 2. Comparison of P90 and MP7 with Test Standard Ammunition Types
Ammunition
Type
Test
Standard /
Level
Bullet
Velocity
(m/s)
Bullet
Mass (g)
Kinetic
Energy (J)
Kinetic
Energy
Density
(J/mm2)
9 mm FMJ
NIJ-0101.06
Level II
398
8.0
713
2.8
.357 SIG
NIJ-0101.06
Level IIIa
448
8.1
813
3.1
.44 Mag
NIJ-0101.06
Level IIIa
436
15.6
1,483
3.8
5.7 28 mm
(P90)
None
715
2.0
540
5.3
4.6 30 mm
(MP7)
None
725
1.6
420
6.3
7.62 51
mm NATO
ball
NIJ-0101.06
Level III
847
9.6
3.444
18.8
These comparisons of kinetic energy and kinetic energy density for the
different ammunition types show clearly that there is no sensible equivalence of
ammunition within the NIJ-0101.06 standard. Other test standards include
similar ammunition types in their levels to those found in the NIJ-0101.06.
Even the VPAM APR 2006 with its 14 levels goes from their level 5 to level 6,
which jump from a .357 (albeit one with a muzzle velocity of 580 m/s) to the
7.62 39 mm PS ball.
These weapons may well be used by police forces whose main protection is
provided by textile body armour. This causes concerns, as the potential for
fratricide now needs to be considered.
5. LOCAL AMENDMENTS TO TEST METHODS
OR STANDARDS
Sometimes an armour specifier will realise that the threats, or more
correctly the test levels, in the test standard are close to their requirement, but
not quite what they need. It is then possible that the specifier will determine that
the test standard may be used, but with some additional minor modification.
A common example of this approach relates to NIJ-0101.04 or NIJ-0101.06
Level III. The level refers to a 7.62 51 mm NATO ball only. This is the lowest
high velocity rifle test level within the NIJ standard.
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Personal Armour Testing versus Small Arms Ammunition when the Test
27
In those cases where the rigid body amour plate is one with a ceramic
strike-face the requirement to defeat the 7.62 51 mm NATO ball at muzzle
velocity would also be expected to defeat ‘lesser’ threats such as the
7.62 39 mm PS ball or the 5.56 45 mm SS109. However, it is now easy to
defeat the 7.62 51 mm NATO ball with a monolithic ultra-high molecular-
weight polyethylene (UHMWPE) plate at a significant reduction in areal
density. However, such a UHMWPE plate will not defeat either the
7.62 39 mm PS ball or the 5.56 45 mm SS109. Therefore the intelligent
specifier who understands this limitation of monolithic UHMWPE will define
an addition to the level in the NIJ and usually refer to it as NIJ Level III+,
which of course does not really exist. This level III+ will include the PS ball
and the SS109, thus forcing the manufacturers to offer a ceramic-faced plate or
a very thick UHMWPE plate.
5.1. Ballistic Helmet Testing
Ballistic helmets are often specified to an NIJ standard. However the
specification is often stated simply as ‘NIJ Level IIIa’. It is rare that the
specification includes which particular NIJ standard the specifier wants the
helmet to be tested to. There is an NIJ standard for ballistic helmets
NIJ-0106.01 [9]. However NIJ-0106.01 only consists of three levels, levels
I, IIA and II, and so there is no level IIIa associated with an NIJ standard for
helmets. When the specifier refers to NIJ Level IIIa they must therefore be
referring to the body armour standard level, or possibly even NIJ-0108.01 [10]
which is the NIJ standard for Ballistic Resistant Protective Materials. Most
ballistic helmets are designed for the defeat of 9 mm FMJ ammunition only.
Therefore with this intended protection level of 9 mm FMJ what are the options
for which test standard are really suitable? NIJ-0101.06 is not an option as it no
longer includes the 9 mm FMJ in level IIIa. The 9 mm FMJ can be found in
level IIIa of NIJ-0101.04 and also in level IIIa of NIJ-0108.01. Therefore it
could be either of these, but the specified velocity and tolerance are different.
In NIJ-0101.04 the velocity for the level IIIa 9 mm FMJ is specified
as 436 ± 9 m/s (427 to 445 m/s), while for the NIJ-0108.01 velocity is specified
as 426 ± 15 m/s (411 to 441 m/s). If a standard is required which is not one
originally written for the item being tested, it is critical that it is fully defined.
It should be fully defined even if it is the relevant standard for the item being
tested.
6. BULLET SURROGATES
In the vast majority of cases in which personal armour is tested versus
a fragmentation threat, a surrogate approach is used.
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P.L. Gotts
28
The ‘real’ fragmentation is produced by some type of exploding munition,
whether conventional or improvised. However it is not these real’ devices, or
even the fragments from them which are used for testing the personal armour.
This is because the ‘real’ devices or fragments are not consistent from
detonation to detonation. Therefore, in order to maintain consistency during the
test process fragment simulating projectiles (FSPs) are used. These FSPs are
delivered to the target by being controllably fired from a gun barrel, and not by
being launched from an explosive munition. The most common FSP geometry
is that of the chisel-nosed cylinder, which was developed at the end of the USA
in the early 1940s [11]. The FSP cannot be considered to be a replicate of all, or
even any, real fragments, but is instead used to allow for consistent and
repeatable testing of armour materials and systems.
If there is a serious issue with both the availability and consistency of
bullets in some types of small arms ammunition, used in either reality or in test
methods and standards, might it be sensible to use bullet simulating surrogates
(BSPs)?
This idea of bullet surrogates has been discussed quite a lot over the last
decade, but it has really only been over the last two years that any serious
development work has been conducted. Two European government
organisations have independently started programmes of work in this area, and
it is interesting to note that the approaches have been completely different.
The UK MOD’s Defence Science and Technology Laboratory (DSTL) has
considered a specific bullet type [12], which is one known to be an issue with
both its availability (in the UK at least) and its variability the 7.62 54R B32
API. The issue was highlighted by Gotts et al [8] at PASS 2010, a paper within
which different sources of B32 API were compared by their V50 performance
versus armoured steel targets. Their design is a near replica of the B32
manufactured in a way that is consistent for each projectile. The main difference
to the original, however, is the non-inclusion of the incendiary component in
either the nose or the tail of the projectile.
The alternative approach is that of the Royal Military Academy in Brussels
[13]. Their approach is to produce a more generic projectile of a specific
calibre, more in line with the thinking behind the FSP. The focus is on
simplicity and hence repeatability of design.
7. SUMMARY
Small arms ammunition which may impact personal armour and is deemed
to be realistic as a threat by the user, may not always comply with armour test
standards. In many cases there are good practical reasons why such realistic
ammunition is not included in standards, including availability and variability.
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Personal Armour Testing versus Small Arms Ammunition when the Test
29
Where reality and the test methods do not line up it may be in the area of
the test levels. Another complicating issue is that of BABT and the
measurement of BFS.
However, when using some test standards, approximate equivalents have
been made between realistic ammunition and those levels available within the
standards, for example, the use of 30.06 AP M2 as an alternative to 7.62 54R
B32 API.
Some weapon systems not represented within test standards, are not
possible to be replaced by any test level listed in any test standard. For example
the Heckler and Koch MP7 and FN P90, which are positioned in performance
between handgun and rifle levels.
Many armour specifiers and users will make minor modifications to levels
in armour standards in order to allow the test method to be valid, but with
slightly different ammunition types included within a specific level. For
example NIJ 0101.06 Level III+ is often specified usually for materials-based
reasons. The use of test standards for ballistic helmets has caused some
confusion, as specifiers use the NIJ standards, but not those designed for
ballistic helmets.
Fragment simulating projectiles have been used since the 1940s. It may
now be time to consider the use of bullet simulating projectiles and there are
now two pieces of work being conducted in this area.
REFERENCES
[1] NIJ Standard-0101.04, Ballistic Resistance of Body Armor NIJ Standard-
0101.04, US Dept of Justice, June 2001.
[2] NIJ Standard-0101.06, Ballistic Resistance of Body Armor NIJ Standard-
0101.06, US Dept of Justice, July 2008.
[3] Croft J., Longhurs T.D., HOSDB Body Armour Standards for UK Police
(2007), Part 2: Ballistic Resistance Publication No 39/07/B, July 2007.
[4] VPAM APR 2006 (English), General Basis for Ballistic Material,
Construction and Product Testing, May 2009.
[5] GOST R 50744-95, Armour Clothing Classification and General
Technical Requirements, GOST Standard, May 2003.
[6] Police Body Armor Standards and Testing Volume II: Appendices
OTA-ISC-535, Aug. 1992.
[7] Fenne P.M., Barnes-Warden J., Developing a test methodology to
moderate levels of injury resulting from BABT, Proceedings of PASS
2014, Sep. 2014.
[8] Gotts P.L., Tawell M.G., Holden S.J., Variations in Ammunition Used
for Testing Personal Armour, Proceedings of PASS 2010, Sep. 2010.
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P.L. Gotts
30
[9] NIJ Standard-0106.01, NIJ Standard for Ballistic Helmets, National
Institute of Justice, Dec. 1981.
[10] NIJ Standard-0108.01, Ballistic Resistant Protective Materials, National
Institute of Justice, Sep. 1985.
[11] Sullivan J.F., Results of Programs on Development of Body Armour
Undertaken at Watertown Arsenal during WWII, Watertown Arsenal
Report, Oct. 1945.
[12] Helliker M., Champion S., Helliker A., Ringrose T., The development of
bullet surrogates for armour testing, Proceedings of PASS 2014, Sep.
2014.
[13] Coghe F., Puddu O., Pirlot M., On the introduction of a bullet simulating
projectile: Experimental feasibility study, Proceedings of PASS 2014,
Sep. 2014.
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... Despite the fact that the system was designed for measuring the BFS of an armour system after an impact, it has different associated problems; one of them is the big scatter of the data. This is due to the large number of factors that can influence the final outcome of a particular test, such as humidity or previous use of the clay [15]. Another issue is the head form itself, as the aluminium part of the surrogate might interact with the deforming helmet, influencing the BFD of the helmet. ...
Article
Currently, ballistic helmets are mostly designed to stop fragments from diverse explosive devices. Nowadays, new requirements have emerged for helmets, such as stopping direct impacts from revolver and pistol threats. The probability of these types of impacts on helmet systems is increasing due to the changes in warfare and military operations. Although, it is possible to stop this kind of projectile, there is a lack of studies regarding the possible injuries suffered by the user due to non-perforating impacts. In this research, a comparison between the results obtained with a clay head form and a head surrogate with force sensors was done to estimate the load force on the skull during an impact. 9 × 19 mm FMJ projectiles were fired against a ballistic helmet to study the indentation and the force generated by the back face deformation against the two different head forms.
Conference Paper
The issue of selecting ammunition for the test and acceptance of armour is a continual problem for manufacturers and procurers alike. Threat ammunition can be difficult to obtain, costly and inconsistent. Nominally identical natures may in reality vary substantially, leading to the case of armour passing tests against one type of round, yet failing against a round manufactured elsewhere. To address this issue, Dstl together with Cranfield University embarked on a programme of developing surrogate bullets for armour testing. The performance of the surrogates has been matched against commonly used bullets in standards. The surrogate projectiles are manufactured to high tolerances to ensure good consistency and are designed to be fired from NATO cartridges and barrels. The subsequent specifications will be made freely available for the purposes of testing armour only. To date a surrogate for the 7.62 x 54R B32 API has been developed, though further refinement and testing is required and testing of the 7.62 x 39 BZ API surrogate is underway.
Conference Paper
Whereas the introduction of a bullet simulating projectile (BSP) to eliminate the use of commercial ammunition during the ballistic evaluation of personal armour systems may seem promising from an organisational point of view, all possible interest stands or falls with the feasibility on comparing and scaling the relevant effects of the commercial ammunition to those observed with the BSP. To this purpose a feasibility study was performed to validate the practical applicability of the BSP method. A first prototype BSP design, representing pistol and revolver threats, was compared to two types of commercial ammunition (9 mm Para and .44 Magnum). The comparison was made both for penetration capacity as for the possibility on inflicting behind-armour blunt trauma (BABT). To quantify the penetration capacity of the projectiles, the ballistic resistance of different configurations, made out of two reference armour materials (mild steel and a unidirectional fibre-based armour material), was measured (V50 approach). The obtained results indicate that the penetration capacity can be quite confidently scaled to an equivalent penetration capacity for the BSP within the statistical errors generally already accepted by the different test standards. The possibility of inflicting BABT was so far only characterized for the BSP and the 9 mm Parabellum, by measuring the depth and volume of the cavity formed in a reference witness material to which a reference armour package had been fitted. Due to the lack of overlapping data between the two projectiles, a direct comparison was difficult, but the feasibility of scaling did not seem impossible, preferably based on a volume measurement. The important penetration capacity of the current BSP design might however require a change in the BSP design (different material) or the introduction of a second BSP design to assess the risk on BABT.
Article
This study reflects tests alone to determine what type of body armor would be best sewn in the flight suits of 8th Air Force pilots in World War 2. The initial idea came from the British and U.S. test improved the armor material. Aluminum alloys, silk and doran (a plastic laminate) were tested as good materials for large plates of flexible body armor. It was determined that future experimentation was to be done in this project.
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